--- a/src/pyams_content/shared/view/__init__.py	Mon Jan 07 11:36:09 2019 +0100
+++ b/src/pyams_content/shared/view/__init__.py	Tue Jan 08 14:02:06 2019 +0100
@@ -9,6 +9,9 @@
 # WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
 # FOR A PARTICULAR PURPOSE.
 #
+from copy import deepcopy
+
+from jedi.evaluate.helpers import deep_ast_copy
 
 __docformat__ = 'restructuredtext'
 
@@ -112,7 +115,7 @@
 
     def get_results(self, context, sort_index=None, reverse=None, limit=None,
                     start=0, length=999, ignore_cache=False, get_count=False, request=None):
-        results = _MARKER
+        results, count = _MARKER, 0
         if not ignore_cache:
             # check for cache
             views_cache = get_cache(VIEWS_CACHE_REGION, VIEWS_CACHE_NAME)
@@ -129,11 +132,13 @@
         # Execute query
         if results is _MARKER:
             registry = get_current_registry()
+            # Look for Elasticsearch query adapter, if available...
             adapter = registry.queryAdapter(self, IViewQuery, name='es')
             if adapter is None:
                 adapter = registry.getAdapter(self, IViewQuery)
             if not sort_index:
                 sort_index = self.order_by
+            # Get query results
             results, count = adapter.get_results(context,
                                                  sort_index,
                                                  reverse if reverse is not None else self.reversed_order,
@@ -189,25 +194,27 @@
             for new_params in adapter.get_params(context, request):
                 if isinstance(new_params, tuple):
                     new_params, do_search = new_params
-                if new_params:
+                if new_params is None:
+                    return None
+                else:
                     params &= new_params
             if not do_search:
                 break
         # activate search
         if do_search:
-            params &= Gt(catalog['push_end_date'], now)
+            filters = Gt(catalog['push_end_date'], now)
             # check content path
             content_path = view.get_content_path(context)
             if content_path is not None:
-                params &= Eq(catalog['parents'], content_path)
+                filters &= Eq(catalog['parents'], content_path)
             # check content types
             content_types = view.get_content_types(context)
             if content_types:
-                params &= Any(catalog['content_type'], content_types)
+                filters &= Any(catalog['content_type'], content_types)
             # check data types
             data_types = view.get_data_types(context)
             if data_types:
-                params &= Any(catalog['data_type'], data_types)
+                filters &= Any(catalog['data_type'], data_types)
         return params
 
     def get_results(self, context, sort_index, reverse, limit, request=None):
@@ -215,14 +222,18 @@
         catalog = get_utility(ICatalog)
         registry = get_current_registry()
         params = self.get_params(context, request)
-        if (not sort_index) or (sort_index == RELEVANCE_ORDER):
-            sort_index = None
-        query = CatalogQuery(catalog).query(params,
-                                            sort_index=sort_index,
-                                            reverse=reverse,
-                                            limit=limit)
-        total_count = query[0]
-        items = CatalogResultSet(query)
+        if params is None:
+            items = CatalogResultSet([])
+            total_count = 0
+        else:
+            if (not sort_index) or (sort_index == RELEVANCE_ORDER):
+                sort_index = None
+            query = CatalogQuery(catalog).query(params,
+                                                sort_index=sort_index,
+                                                reverse=reverse,
+                                                limit=limit)
+            total_count = query[0]
+            items = CatalogResultSet(query)
         for name, adapter in sorted(registry.getAdapters((view,), IViewQueryFilterExtension),
                                     key=lambda x: x[1].weight):
             items = adapter.filter(context, items, request)